U.S. patent number 7,946,280 [Application Number 12/176,792] was granted by the patent office on 2011-05-24 for method for the operation of an internal combustion engine.
This patent grant is currently assigned to Robert Bosch GmbH. Invention is credited to Pierre-Yves Crepin, Emilie Hincker-Piocelle, Karsten Kroepke, Ruediger Weiss, Jens Wolber.
United States Patent |
7,946,280 |
Wolber , et al. |
May 24, 2011 |
**Please see images for:
( Certificate of Correction ) ** |
Method for the operation of an internal combustion engine
Abstract
The invention deals with a method for the operation of an
internal combustion engine with at least two cylinders, which can
be operated with a fuel of variable quality stored in a tank and/or
with fuel blends stored in the tank from a first and at least a
second fuel in variable mixing ratios, and wherein variable fuel
qualities and/or fuel blends of different compositions require
variable air/fuel ratios for the achievement of a stable combustion
and/or have a variable vaporization behavior. Provision is,
thereby, made for a variation, which is individually adjusted to
each cylinder, of the quantity of fuel delivered to the cylinder to
be implemented to supply a lean and/or to a rich air/fuel mixture
at least one cylinder, for the effect of the variation on the
starting characteristics and/or the running smoothness of the
cylinder and/or the internal combustion engine to be evaluated and
when an improvement in the starting characteristics and/or the
running smoothness is achieved, for a fuel adaptation to be
implemented for all cylinders. The method makes the quick detection
and the avoidance of starting problems possible, when a change in
the fuel quality or in the fuel composition occurs with an effect
on the ignitability of the fuel.
Inventors: |
Wolber; Jens (Gerlingen,
DE), Weiss; Ruediger (Moetzingen, DE),
Hincker-Piocelle; Emilie (Ludwigsburg, DE), Kroepke;
Karsten (Ludwigsburg, DE), Crepin; Pierre-Yves
(Stuttgart, DE) |
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
40157322 |
Appl.
No.: |
12/176,792 |
Filed: |
July 21, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090025695 A1 |
Jan 29, 2009 |
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Foreign Application Priority Data
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Jul 27, 2007 [DE] |
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10 2007 035 317 |
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Current U.S.
Class: |
123/575; 123/434;
123/1A; 123/672 |
Current CPC
Class: |
F02D
19/088 (20130101); F02D 41/008 (20130101); F02D
41/0025 (20130101); F02D 19/061 (20130101); F02D
41/1498 (20130101); F02D 2200/0612 (20130101); Y02T
10/30 (20130101); F02D 41/2451 (20130101); F02D
41/062 (20130101); F02D 41/0085 (20130101); F02D
19/084 (20130101); F02D 19/0628 (20130101) |
Current International
Class: |
F02B
13/00 (20060101) |
Field of
Search: |
;123/1A,434,435,575,576,672 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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41 17 440 |
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Dec 1991 |
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DE |
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WO 00/65217 |
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Nov 2000 |
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WO |
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Primary Examiner: Kwon; John T
Attorney, Agent or Firm: Merchant & Gould P.C.
Claims
The invention claimed is:
1. A method of operating an internal combustion engine having at
least two cylinders capable of operating with anyone of a fuel of
variable quality stored in a tank or with and a fuel blend stored
in the tank, wherein the fuel blend is mixed in a variable ratio
from a first and at least a second fuel, and wherein the fuel of
variable qualities and the fuel blends of different compositions
either require a variable air/fuel ratio for the achievement of a
stable combustion or have a variable vaporization behavior, the
method comprising: varying a quantity of fuel delivered to the at
least two cylinders in at least one of the cylinders to supply one
of a lean and a rich air/fuel mixture, wherein the fuel quantity
variation is individually adjusted to each of the at least two
cylinders; evaluating the effect of the fuel quantity variation on
at least one of a starting characteristic and a running smoothness
of any one of each of the at least two cylinders and the internal
combustion engine; and implementing a fuel adaptation for all
cylinders based on the fuel quantity variation achieving an
improvement in at least one of the starting characteristic and the
running smoothness.
2. A method according to claim 1, further comprising individually
varying the quantity of fuel delivered to the at least two
cylinders in at least one of the cylinders when the internal
combustion engine is started or in an afterstart phase.
3. A method according to claim 1, further comprising individually
varying the quantity of fuel delivered to the at least two
cylinders in at least one of the cylinders if one or more of the
following conditions are satisfied: a. after a detected filling of
the tank; b. the fuel adaptation has not yet been implemented; c.
the internal combustion engine experiences a starting problem; or
d. an uneven running of the internal combustion engine is
detected.
4. A method according to claim 1, further comprising implementing
the evaluation of the starting characteristic using a rotational
speed progression of the internal combustion engine during a
starting phase.
5. A method according to claim 1, further comprising implementing
the individual variation of the quantity of fuel delivered to the
at least two cylinders in at least one of the cylinders during one
or more combustion strokes.
6. A method according to claim 1, further comprising: ascertaining
a filling of the tank, a fill level of the tank and a mixing ratio
prevailing in the tank between the first and the second fuel prior
to the filling of the tank; ascertaining a quantity of fuel added
to the tank; when a filling of the tank is detected, assuming that
the tank is filled with a fuel blend having an assumed mixing ratio
between the first and the second fuel; calculating an assumed
mixing ratio prevailing in the tank resulting from said filling of
the tank, wherein the step of individually varying the quantity of
fuel delivered to the at least two cylinders in at least one of the
cylinders is made such that there is a suitable air/fuel mixture
for the assumed mixing ratio prevailing in the tank.
7. A method according to claim 6, wherein the assumed mixing ratio
added to the tank corresponds to one of a fuel blend from at least
approximately equal percentages of the first fuel and the second
fuel and a fuel blend from at least approximately equal percentages
of a first fuel and a specified blend from the first and the second
fuel.
8. A method according to claim 1, wherein the fuel adaptation is an
adaptation of one or more operating parameters of the internal
combustion engine to a composition of one or more of the following
fuel blends: a. gasoline/ethanol; b. gasoline/methanol; c.
gasoline/ethanol/methanol; and d. diesel/biodiesel fuel blend.
9. A method according to claim 1, wherein the fuel adaptation is an
adaptation of one or more operating parameters of the internal
combustion engine to a gasoline quality prevailing in the tank.
Description
TECHNICAL FIELD
The invention deals with a method for the operation of an internal
combustion engine with at least two cylinders, which can be
operated with a fuel of variable quality stored in a tank and/or
with fuel blends from a first and at least a second fuel in
variable mixing ratios, and wherein variable fuel qualities and/or
fuel blends of different compositions require variable air/fuel
ratios for the achievement of a stable combustion and/or have a
variable vaporization behavior.
BACKGROUND
When starting internal combustion engines, which are based on the
principle of the gasoline engine, the metering of the fuel quantity
to be injected plays a decisive role in the ignitability of the
air/fuel mixture as well as in the exhaust gas composition. The
required fuel quantity depends greatly on the fuel characteristics,
especially on the vaporization characteristics of the fuel.
An air/fuel ratio, which is too lean, can, for example, be detected
via the evaluation of the engine rotational speed using a start
quantity adaptation. Using an afterstart adaptation, the uneven
running of the internal combustion engine is evaluated. Immediately
following said adaptation, a poor vaporization behavior of the fuel
can be compensated for with a mixture enrichment.
Internal combustion engines based on the principle of the gasoline
engine are generally operated with fuel from hydrocarbons, which
are derived from fossil fuels on the basis of refined crude oil.
Alcohol produced from renewable resources (plants), for example
ethanol or methanol, is increasingly being added in various mixing
ratios to this fuel. In the USA and Europe a mixture of 75-85%
ethanol and 15-25% gasoline is often distributed under the trade
name E85. The internal combustion engines are designed in such a
way that they can be operated with pure gasoline as well as with
blends up to E85. This is denoted as a "flex-fuel operation".
As a result of the arbitrary mixture of gas and alcohol, a broad
spectrum of variations of the fuel characteristics arises,
especially of the fuel stoichiometry and the vaporization
behavior.
From the German patent DE 4117440 C2, a method is known for the
adaptive adjustment of a fuel/air mixture to take into account the
fuel characteristics in the operation of an internal combustion
engine, which has a lambda controller, which emits a control factor
RF, and which has an adaptation integrator, which emits and
adaptation factor AF with variable adaptation speed. Said
adaptation factor AF with the control factor RF influences the
adjustment of the fuel/air mixture. In so doing, provision is made
for a test to determine whether the lambda closed-loop control
deviation amplitude exceeds a first threshold value. If this is the
case, the adaptation speed is set at an increased value up until a
specified condition is met. Thereafter it is shifted back to a
lower adaptation speed.
The method makes the trouble-free operation of internal combustion
engines possible, which can be operated with variable fuels. Thus,
the duration of injection must, for example, be extended by more
than 20%, when a change is made from a fuel of pure gasoline to a
fuel containing 85% ethanol and 15% gasoline. In so doing, the same
lambda values can be maintained in the exhaust gas. According to
the method described in the text of the German patent DE 4117440
C2, a corresponding adaptation intervention is additionally
performed. Because in comparison to the compensation for the
influences of wear and manufacture, a very significant correction
of the durations of injection and thereby of the adaptation
intervention must be performed when a refueling of the tank takes
place, the adaptation speed is significantly increased in the
proposed method when a refueling has been detected.
On the basis of the adjusted adaptation value, the fuel mixture
ratio can be determined. Despite the increased adaptation time, the
method requires a sufficiently long settling time. If a significant
change in the fuel mixture ratio is caused by the filling of the
tank (fueling), this can lead to starting difficulties and to
misfires, which in turn lead to increased exhaust gas
emissions.
Beside a change of the fuel mixing ratio of an internal combustion
engine operated in the flex-fuel mode, a variation in the fuel
quality can also, for example, lead to difficulties in starting in
the pure gasoline operating mode. In this instance, the fuel
quality especially has an effect on the vaporization
characteristics of the fuel. When the alcohol percentage in the
fuel is not known, it is difficult to distinguish between the two
aforementioned causes. An enrichment of the air/fuel mixture as a
reaction to the poor starting performance of the internal
combustion engine, as it is known from the pure gasoline operating
mode, is for this reason not always appropriate when applied to the
flex-fuel mode.
It is the task of the invention to provide a method, which allows
for a reliable starting of the internal combustion engine when the
fuel mixing ratio is not known or when the fuel quality is not
known.
SUMMARY
The task of the invention is thereby solved; in that at least at
one cylinder, a variation, which is individually adjusted to each
cylinder, of the quantity of fuel delivered to the cylinder is
implemented by making the air/fuel mixture leaner or richer; in
that the effect of the variation on the starting characteristics
and/or on the running smoothness of the cylinder and/or the
internal combustion engine is evaluated and in that when an
improvement in the starting characteristics and/or in the running
smoothness is achieved, a fuel adaptation is implemented for all
cylinders. The method makes it possible to implement a comparison
of the starting characteristics and/or the running smoothness
between the cylinders, which are operated with different operating
parameters, and to transfer the best operating parameters for the
prevailing fuel to the rest of the cylinders.
In so doing, the change in the characteristics of the fuel can be
suggested when comparing the original operating parameters with the
new operating parameters. For example, an inference can be made
whether a fuel with a more significant vaporization prevails or if
the mixing ratio of a prevailing fuel mixture has changed. By means
of its quick implementability already during the starting phase,
the method first of all allows for a reliable starting of the
internal combustion engine. It furthermore prevents that the
internal combustion engine quits in the phase after the starting
procedure. If need be, a more exact adaptation of the fuel
characteristics can take place via known methods in the subsequent
operational mode of the internal combustion engine.
A variation, which is individually adjusted to each cylinder, of
the quantity of fuel delivered to the cylinder can be implemented
at one or several cylinders in comparison to the existing settings,
with which one or several additional cylinders are being operated.
Moreover, it is possible to change the injected fuel quantity at
different cylinders in the opposite direction in order to establish
a suitable direction of adaptation.
If provision is made for the variation, which is individually
adjusted to each cylinder, of the quantity of fuel delivered to the
cylinder to be implemented during starting of the internal
combustion engine and/or in a post starting phase, a reliable
starting of the engine as well as a reliable operational mode of
the engine is assured until a more exact fuel adaptation by the
engine management system has been implemented.
If provision is additionally made for the variation, which is
individually adjusted to each cylinder, of the quantity of fuel
delivered to the cylinder to be implemented after a detected
filling of the tank (fueling) and/or when a fuel adaptation has not
yet been implemented and/or when starting difficulties of the
internal combustion engine occur and/or when an uneven running of
the internal combustion engine is detected after starting, a
manipulation of the operating parameters of the internal combustion
engine is then only performed if a change in the fuel
characteristics can be assumed. A distinct change in the fuel
characteristics generally assumes that a filling of the tank
(fueling) has taken place. Fuel with the new fuel characteristics
will arrive at the internal combustion engine from the tank after a
certain time of flow. This can occur during the normal operation of
the internal combustion engine as well as during a starting phase
or in a phase immediately after starting the internal combustion
engine. In this instance, a more rapid compensation for the altered
fuel characteristics can take place by means of the method
according to the invention. If a fuel adaptation has already taken
place since the tank was filled, the fuel characteristics are thus
adequately known, for example the composition of a fuel blend, in
order to guarantee a reliable starting and operation of the
internal combustion engine. If starting difficulties or an uneven
running of the internal combustion engine nevertheless occur, an
unknown reason for the change in the fuel characteristics can thus
be assumed. For example, a filling of the tank (fueling) can have
gone undetected.
A simple and reliable detection of starting problems of the
internal combustion engine is thereby possible with existing
sensors and sensor data, so that an evaluation of the starting
characteristics is implemented using the rotational speed
progression of the internal combustion engine in the starting
phase. The engine rotational speed, respectively the engine
rotational speed progression, can thereby be compared with
specified values or value ranges.
The declaration reliability of the method can thereby be
influenced, in that the variation, which is individually adjusted
to each cylinder, of the quantity of fuel delivered to the cylinder
is implemented during a combustion stroke or during several
combustion strokes. Especially if a well-founded suspicion of a too
lean or a too rich air/fuel mixture exists, it is advantageous if
one or several of the cylinders of the internal combustion engine
are repeatedly operated in a rich state, respectively lean
state.
According to an especially preferred variation of embodiment of the
invention, provision can be made for a filling of the tank
(fueling) and the fill level of the tank and the mixing ratio
between the first and the second fuel existing in the tank before
the filling of the tank (fueling) to be ascertained, for a quantity
of fuel added to the tank during fueling to be ascertained, for a
filling of the tank (fueling) with a fuel blend, which was added in
an accepted mixing ratio between the first and the second fuel, to
be assumed when a detected filling of the tank (fueling) has
occurred, for a mixing ratio in the tank to be calculated, which
can be assumed to have resulted from said filling of the tank
(fueling) and for the variation, which is individually adjusted to
each cylinder, of the quantity of the fuel delivered to the
cylinder to take place to the effect that an air/fuel mixture
exists suited to the mixing ratio, which can be assumed to have
resulted from said filling of the tank (fueling). A possible change
in the fuel mixture ratio and consequently in the fuel
characteristics can be suggested from the detected filling of the
tank (fueling). The mixing ratio existing in the tank before the
filling of the tank (fueling) is known, for example, from a fuel
adaptation implemented during the operation of the internal
combustion engine. If the quantity of fuel added is additionally
known, an assumed fuel composition in the tank resulting from said
filling of the tank (fueling) can be calculated for an assumed
composition of the added fuel. From the deviation of this assumed
fuel composition, which resulted from said filling of the tank
(fueling), from the fuel composition before the filling of the tank
(fueling), a necessary change in the quantity of fuel delivered to
the cylinder can be determined. In a subsequent evaluation of the
starting characteristics, respectively the running smoothness in an
afterstart phase, it can be determined whether the change in the
quantity of fuel delivered, which is adjusted individually to each
cylinder, took place in the right direction, for example toward a
richer air/fuel mixture. If this is the case, the quantity of fuel
delivered can likewise be correspondingly changed for the other
cylinders.
If provision is thereby made for the assumed mixing ratio of the
fuel added to the tank to correspond to a fuel blend from at least
approximately equal percentages of the first fuel and the second
fuel and/or for the assumed mixing ratio of the fuel added to the
tank to consist of a fuel blend from at least approximately equal
percentages of a first fuel and a specified blend from the first
and second fuel, fuel characteristics for the assumed fuel blend
added to the tank thus arise, which lie approximately in the middle
of the possible fuels added to the tank. Therefore, in Europe it is
only possible to fuel the tank either with pure gasoline E0 or with
E85, i.e. a specified blend consisting of 85% ethanol and 15%
gasoline. The method lends itself then to be advantageously
implemented with an assumed mixing ratio of E40 of the fuel added
to the tank, which corresponds to a blend of approximately equal
percentages of E0 and E85.
The method advantageously lends itself to be used for the
adaptation of the operating parameters of an internal combustion
engine to the composition of a gasoline/ethanol fuel blend and/or a
gasoline/methanol fuel blend and/or a diesel/biodiesel fuel
blend.
In addition the method advantageously lends itself to be used for
the adaptation of the operating parameters of the internal
combustion engine to a prevailing gasoline quality.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained below in detail using one of the
examples of embodiment depicted in the FIGURE. The following is
shown:
FIG. 1 is a flow diagram for the fuel adaptation in the starting
phase of an internal combustion engine.
DETAILED DESCRIPTION
FIG. 1 shows a flow diagram 1 for the fuel adaptation in the
starting phase of an internal combustion engine, which can be
operated with gasoline or a blend of gasoline and ethanol.
A first block: start internal combustion engine 10 is followed by a
junction: poor engine rotational speed progression 20 with the
branches: yes, poor engine rotational speed progression 30 and: no,
poor engine rotational speed progression 31. The branch: yes, poor
engine rotational speed progression 30 leads to a further junction:
filling of the tank (fueling) detected 21, which leads with the
branch: yes, filling of the tank (fueling) detected 32 to a block:
presumption fuel E40 11, while a branch: no, filling of the tank
(fueling) detected 33 leads to a block: lean out/richen 14. A
junction: ethanol content >60% 22 is subsequent to the block:
presumption fuel E40 11. Said junction leads with a branch: yes,
ethanol content >60% 34 to a block: lean out individual
cylinders 12 and with a branch: no, ethanol content >60% 35 to a
further junction: ethanol content <20% 23. A branch: yes,
ethanol content <20% 36, which starts from this junction, leads
to a block: richen individual cylinders 13; and a branch: no
ethanol content <20% 37, which starts from said junction
proceeds together with the branch: no, filling of the tank
(fueling) detected 33 to the block: lean out/richen 14. The blocks:
lean out individual cylinders 12, richen individual cylinders 13
and lean out/richen 14 are connected to a block: evaluate engine
rotational speed 15, which in turn leads to a junction: improvement
in engine rotational speed progression 24. A branch: no,
improvement in engine rotational speed progression 39 leads back
again to the front end of the junction: filling of the tank
(fueling) detected 21. A branch: yes, improvement in engine
rotational speed progression 38 leads on the other hand to a block:
adoption of operating parameters 16, and proceeds from there to a
block: storage 17 and finally to a block: end 18, which is also fed
by the branch: no, poor engine rotational speed progression 31.
The starting of the internal combustion engine takes place in the
block: start internal combustion engine 10. At the junction: poor
engine rotational speed progression 20, a test is made using the
progression of the rotational speed during the start-up of the
internal combustion engine and using the running smoothness of the
internal combustion engine in the phase immediately after the
starting of the internal combustion engine to determine whether
starting problems or afterstart problems exist. If no such starting
problems, respectively afterstart problems, exist, the flow diagram
jumps over the branch: no, poor engine rotational speed progression
31 to the block: end 18 without performing a change in the
operating parameters of the internal combustion engine or of
individual cylinders of the internal combustion engine. If on the
other hand starting problems, respectively afterstart problems are
detected, the flow diagram proceeds via the branch: yes, poor
engine rotational speed progression 30 to the junction: filling of
the tank (fueling) detected 21. A test is made here to determine
whether a filling of the tank (fueling) was detected and/or whether
a fuel adaptation has not yet taken place or has not yet been
completed. If none of these conditions are met, the cause for the
starting problems is not clear. In this case, a branching out
occurs via the branch: no, filling of the tank (fueling) detected
33 to the block lean out/richen 14. If on the other hand a filling
of the tank (fueling) is detected without a corresponding fuel
adaptation having been implemented, the flow diagram follows the
branch: yes, filling of the tank (fueling) detected 32 to the
block: presumption fuel E40 11. A presumption occurs in this block
that the fuel added to the tank has a mixing ratio of 40% ethanol
and 60% gasoline. A fuel blend with this mixing ratio is denoted as
E40. The mixing ratio E40 lies in the middle of the major fuels in
Europe and the USA: pure gasoline E0 and ethanol/gasoline E85 with
a mixing ratio 85% ethanol and 15% gasoline. Under this
presumption, the flow diagram leads to a junction: ethanol content
>60% 22.
At this junction, a test is made to determine whether the ethanol
content of the fuel blend in the tank was greater than 60% before
filling the tank (fueling). The ethanol content before filling the
tank (fueling) was ascertained, for example, in the process of the
normal engine operation by means of a fuel adaptation with the aid
of a lambda probe. If an ethanol content >60% existed, the flow
diagram follows the branch: yes, ethanol content >60% 34 to the
block: lean out individual cylinders 12. If an ethanol content of
the fuel blend before filling the tank (fueling), which is over
60%, is deposited, a blend of E40 is assumed to have been added to
the tank; so that the assumed mixing ratio in the tank, which has
resulted after the filling of tank (fueling), has an ethanol
content, which is smaller than 60%. Consequently provision should
be made for a smaller quantity of fuel to be metered to the
internal combustion engine in comparison to the E60 blend. This
leads to the decision to operate one or several cylinders with a
leaned-out air/fuel mixture and to check this measure in the
subsequent block: evaluate engine rotational speed 15 and at the
junction: improvement in engine rotational speed progression
24.
This sequence in the flow diagram according to the invention is
clearly pointed out below in the concrete numerical example. The
example assumes that a fuel blend of E80 is present in the tank
before filling (fueling) and that a fuel of E0, i.e. pure gasoline,
is added. As a result, a quantitative ratio of 20% E80 to 80% E0
prevails in the tank, which leads to a fuel blend of E16. After the
filling of the tank (fueling), the internal combustion engine is
started and then turned off exactly when the new fuel mixture has
arrived in a rail of the internal combustion engine. When
restarting the internal combustion engine, the ethanol content is
therefore not known. The start-up with the operating parameters for
an E80 blend leads to starting problems. According to the sequence
in the flow diagram, it is assumed in a first presumption after a
detected filling of the tank (fueling) that a blend of E40 was
added to the tank, which lies in the middle of the possible range
of E0 to E85. A new blend of E48, i.e. a transition from a previous
E80 to E48, is therefore assumed. This does not correspond to the
actual composition of E16; however, relative to the original blend
of E80, the direction of the assumed change is correct. If,
therefore, on the basis of the assumptions made, one or several
cylinders is operated with a smaller fuel percentage, this then
leads to improved starting and to a greater running smoothness in
the afterstart phase, which can be proved by way of an evaluation
of the engine rotational speed progression in each individual
cylinder.
If it is determined at the junction: ethanol content >60% 22
that the ethanol content was smaller than 60% before the filling of
the tank (fueling), the procedure proceeds via the branch: no,
ethanol content >60% 35 to a test at a further junction: ethanol
content <20% 23 to determine whether the original ethanol
content was less than 20%. If this is the case, the sequence
proceeds via the junction: yes, ethanol content <20% 36 to the
block: richen individual cylinders 13. Because under the
presumption that a blend of E40 was added to the tank, the assumed
mixing ratio after the filling of the tank (fueling) has a higher
ethanol content than the blend before the filling of the tank
(fueling); a leaning-out of the air/fuel mixture of the individual
cylinders is performed in the block: richen individual cylinders 13
as a measure for the improvement in the starting characteristics.
This measure is in turn checked in the subsequent block: evaluate
engine rotational speed 15 and at the junction: improvement in
engine rotational speed progression 24.
The sequence in the flow diagram according to the invention is
clearly pointed out for this situation using a numerical example:
The example assumes that a fuel of E0 was present in the tank
before a filling of the tank (fueling) and that a fuel blend of E20
was added. In so doing, a quantitative ratio of 20% E0 to 80% E20
prevails, which leads to a fuel blend of E16. After the filling of
the tank, the internal combustion engine is started and then turned
off exactly when the new fuel mixture has arrived in the rail of
the internal combustion engine. When restarting the internal
combustion engine, the ethanol content is therefore not known. The
start-up with the operating parameters for an BO fuel leads to
starting problems. According to the sequence in the flow diagram,
it is assumed in a first presumption after a detected filling of
the tank (fueling) that a blend of E40 was added to the tank, which
lies in the middle of the possible range of E0 to E85. A new blend
of E32, i.e. a transition from a previous E0 to E32, is therefore
assumed. This does not correspond to the actual composition of E16;
however, relative to the original fuel E0, the direction of the
assumed change is correct. If, therefore, on the basis of the
assumptions made, one or several cylinders is operated with a
higher fuel percentage, this then leads to improved starting and to
a greater running smoothness in the afterstart phase, which can be
proved by way of an evaluation of the engine rotational speed
progression, which is adjusted to each individual cylinder.
If it is determined at the junction: ethanol content <20% 23,
which is juxtaposed to the junction: ethanol content >60% 22,
that the ethanol percentage before the filling of the tank
(fueling) was not smaller than 20%, the ethanol content before the
filling of the tank (fueling) then lies in the range between 20%
and 60%. Under a presumption of an added fuel blend of E40, the
cause for the starting problems is then not known; the branch: no,
ethanol content <20% 37 leads the sequence in the flow diagram
to the block: lean out/richen 14. If the cause for the starting
problems is not known, no recommendation for a leaning-out or
richening of individual cylinders can be specified. In the block:
lean out/richen 14, some of the cylinders are, thus, operated with
a richer air/fuel mixture; while other cylinders are supplied with
a leaner air/fuel mixture. The one of the two measures, which leads
to a better starting performance, respectively to a greater running
smoothness in the afterstart phase, is tested in the subsequent
block: evaluate engine rotational speed 15 and at the junction:
improvement in engine rotational speed progression 24.
It is assumed according to a concrete numerical example for this
sequential pathway that a fuel blend of E40 was present in the tank
prior to the filling of the tank (fueling) and that a fuel blend of
E80 was added. The quantitative ratio amounts to 50% E40 and 50%
E80, which leads to a blend of E60. Also in this instance, the
internal combustion engine is started after the filling of the tank
(fueling) and then turned off exactly when the new fuel mixture
arrives in the rail of the internal combustion engine. When
restarting the internal combustion engine, the ethanol content is
therefore not known. According to the sequence in the flow diagram,
it is assumed in a first presumption that a blend of E40 was added
to the tank. Therefore, a new blend of E40, i.e. no change, is
assumed. Actually the fuel composition in the tank changes from E40
to E60. For this reason, a tendency cannot be derived from the
assumption made with regard to the direction a quantity of fuel
delivered to a cylinder should be changed. Starting problems can
arise when starting the internal combustion engine with the
operating parameters for a blend of E40. Because it is not known
whether the blend is too rich or too lean, some cylinders are
richened, while others, on the other hand, are leaned out. In a
subsequent evaluation of the engine rotational speed, which is
individually adjusted to each cylinder, an assessment can be made
about which of the measures led to an improvement in the starting
characteristics.
In the block: evaluate engine rotational speed 15, the progression
of the engine rotational speed for the individual cylinders is
evaluated. In the subsequent branch: improvement in the engine
rotational speed progression 24, a test is made to determine
whether the measures taken have led to an improvement in the
starting performance of the internal combustion engine. If this is
not the case, the sequence of the flow diagram is led back via the
branch: no, improvement in the engine rotational speed progression
39 to the junction: filling of the tank (fueling) detected 21, and
the procedure is again run through. If, on the other hand, an
improvement in the engine rotational speed is established, the
procedure is thus led via the branch: yes, improvement in the
engine rotational speed progression 38 to the block: adoption of
operating parameters 16. In this block, the measures, which led to
an improvement in the starting and/or running characteristics of
the internal combustion engine during the variation of the
operating parameters (especially of the quantity of fuel
delivered), which is adjusted to each individual cylinder, are
transferred to all other cylinders. In an optional following block:
storage, the newly ascertained values can, for example, be stored
as special richening, respectively special leaning-out. After the
improvement in the starting characteristics of the internal
combustion engine, which have been achieved in this manner, the
sequence in the flow diagram is concluded in the subsequent block:
end 18.
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